If a ray of light enters from a rarer medium to a denser medium at zer

If a ray of light enters from a rarer medium to a denser medium at zero angle of incidence, it would

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reflect back.

go straight.

turn towards right.

bend at 45°.

Answer is Right!

Answer is Wrong!

This question was previously asked in

UPSC NDA-1 – 2021

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The correct answer is (B) go straight.

When a ray of light is incident normally (at zero angle of incidence) on the boundary between two different media, it passes from one medium to the other without changing its direction, regardless of whether it is moving from a rarer to a denser medium or vice versa. The angle of incidence is the angle between the incident ray and the normal to the surface. If this angle is zero, the angle of refraction (the angle between the refracted ray and the normal) will also be zero, as predicted by Snell’s Law (n1 sinθ1 = n2 sinθ2).

Snell’s Law states that the ratio of the sine of the angle of incidence to the sine of the angle of refraction is constant for a given pair of media. If θ1 = 0, then sinθ1 = 0. Thus, n2 sinθ2 = 0. Since n2 (refractive index of the second medium) is not zero, sinθ2 must be zero, which means θ2 = 0. Therefore, the refracted ray also lies along the normal, meaning it goes straight. Some partial reflection may occur at the boundary, but the transmitted light goes straight.

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